Many patients experience the development of a stricture or blockage within the ureter of one or both kidneys. The ureter is the muscular tube that connects the kidney to the bladder. As urine is made by the kidney it drains into a central collecting system of the kidney and then travels though the ureter into the bladder. Patients can develop strictures, or blockages, of the ureter due to kidney stones, cancers, infections, trauma, and prior medical instrumentations. In rare instances, some children are born with blockages of one or both ureters. If untreated, the blockage will eventually lead to kidney failure.
Regardless the cause, the treatment for a blocked ureter is to relieve the blockage. Blockage removal is performed by inserting a long tube to connect the collecting system of the kidney to the bladder. This tube is called a stent and is placed through the ureter.
Stent insertion is typically performed by one of two methods. The stent may be inserted urologically. With this method, a scope is advanced through the urethra into the bladder. A wire is then inserted into the ureter in a retrograde fashion, using the scope to thread the wire. When the wire reaches the collecting system of the kidney, a plastic stent is inserted over the wire. The stent is a straight plastic tube that has a pigtail-shaped curl on each end. Once in place, the wire is removed and the scope is taken out of the bladder. One pigtail curl of the stent resides in the collecting system of the kidney and the other resides in the bladder. The straight portion of the stent traverses the ureter. This is performed using direct visualization with the scope and also with fluoroscopic guidance. The stent usually stays in for a period of approximately three months, at which point the stent is then swapped out for a new stent by the urologist using a similar technique.
The second method for insertion is to insert the stent percutaneously. This method is typically performed in stages. The right or left flank of the patient is sterilely prepared depending upon which kidney is to be accessed (sometimes both are accessed to treat bilateral blockages). Intravenous sedation is used. A small bore needle is used to puncture the collecting system of the kidney and contrast is injected allowing the complete visualization of the entire collecting system. The central portion is initially punctured with a small needle, and then a larger needle is used to puncture a smaller but safer area of the collecting system. A guidewire is threaded into the collecting system of the kidney and a pigtail drain, or nephrostomy catheter, is placed, sutured to the back, and hooked up to a bag for external drainage. Once the urine has cleared from bleeding, the patient is brought back to the angiography table, placed prone, and a wire is inserted through the catheter into the kidney. The catheter is then removed. The wire is threaded through the ureter into the bladder (across the stricture) and a nephroureteral catheter is placed.
A nephroureteral catheter is a long plastic tube that goes from the outside of the patient into the kidney's collecting system, through the ureter, and into the bladder. The catheter allows drainage of urine into the bladder and externally into a bag. The catheter typically stays in the patient for 7-10 days, at which time the patient is brought back to the angiography table and a wire is threaded through this tube into the bladder. The tube is removed and an internal stent is placed using fluoroscopic guidance. This is the same type of stent that is placed by the urologist working through the bladder. This can be a complex and difficult procedure.